Automatic block signal system for railroads



MayZ, 1939. D. J. MURPHY AUTOMATIC BLOCK SIGNAL SYSTEM FOR RAILROADS Filed Nov. 14, 1936 2 Sheets-Sheet l May 2, 1939. D. J. MURPHY AUTOMATIC BLOCK SIGNAL SYSTEM FOR RAILROADS Filed Nov. 14, 1936 2 Sheets-Sheet 2 ATTORN EY Patented May 2, 1939 AUTOMATIC BLOCK SIGNAL SYSTEM FOR I RAILROADS Daniel J. Murphy, Chili, N. Y., assiginor to General Railway Signal Company, Rochester, N. Y.

Application November 14, 1936, Serial No. 110,860

5 Claims.

This invention relates to automatic block signal systems and has particular reference to a four indication signal system employing a minimum number of line wires.

In automatic block signal systems it is expedient to employ a minimum number of line circuits between signal locations both because of the cost of line wire as well as the increased cost of maintenance of a larger number of wires over the considerable distances between adjacent signal locations.

With this and other considerations in view it is proposed in accordance with this invention to provide a four indication automatic block signal system operable over a two-wire line circuit. In order to accomplish this it is proposed to employ signals having two indicators and control one of these indicators by direct current applied to the line circuit and control the other indicator by alternating current superimposed on the same line circuit.

Another purpose of this invention is to provide means for operating the signal indicators in the event of a failure of the normal alternating current supply.

Other purposes, objects and characteristic features of this invention will be in part obvious from the accompanying drawings and in part pointed out as the description of the invention progresses.

'In describing the invention reference will be made to the accompanying drawings which when placed end to end with Fig. l to the right of Fig. 2 and with corresponding numbered lines in alignment, constitutes a drawing which shows the invention applied to a stretch of single track which has been divided by the usual insulated joints into four sections or blocks l, 2, 3 and 4 with an arrow indicating the direction of traffic over the trackway. These drawings illustrate only a part of a complete signal system and some of the relays and circuits have been omitted to simplify the illustration.

For the purpose of further simplifying the illustration and facilitating in the explanation thereof, various parts and circuits constituting the embodiment of the invention have been shown diagrammatically and certain conventional illustrations h ave been employed. The drawings have been made with the idea of making clear the purposes and principles of the invention together with the mode of operation rather than with the idea of construction and arrangement of parts that would. probably be employed in practice.

Symbols and are employed to indicate the positive and negative terminals respectively of suitable batteries or other sources of direct current and those terminals with which these symbols are used are presumed to have current flowing from the positive terminal desig hated to the negative terminal designated Where alternating current is used the symbols (i) and (l) are employed to designate the polarities at the respective terminals of a suit-- able source of alternating current.

Symbols employed with any one circuit are considered to designate a single source of energy inthe embodiment of the present invention but as many sources may be provided as found necessary or expedient in practicing the invention.

Apparatus Referring to Fig. l of the accompanying drawings the trackway has been shown divided into track sections i, 2 and 3 by the usual insulated joints, sections I and 2 and the adjacent end of section 3 being shown. At the entrance ends of sections 1 and 2, signals S and S conveniently referred to as two arm signals, are shown, each arm being a search light type signal such as disclosed in Patent No. 1,835,150, issued December 8, 1931, to O. S. Field. Since the apparatus associated with these signals as well as the apparatus associated with signals S and S in Fig. 2, are the same at each signal location it will suffice to describe the apparatus at one signal location, like parts at other signal locations being designated by like reference characters having distinctive exponents.

Referring to the signal apparatus located at the entrance to section I or at signal S the top or upper arm of signal S has been designated by the reference characterUA and has a movable element or rotor B which is controlled in accordance with the polarity of the direct current applied to an operating winding l Rotor 6 has been shown carrying a spectacle containing a green lens G, a red lens R, and a yellow lens Y, the rotor being biased to position the red lens R at the focal point of the light beam from a lamp L when the operating winding 1 of signal UA is deenergized.

The search light type signal UA has movable contacts 8 and 9 contact 8 being in engagement with. the stationary contact ifi when the signal displays a green indication and is in engagement with the stationary contact H when the signal displays a yellow or red indication whereas contact 9 is in engagement with the stationary contact l2 when the signal displays a yellow indication and is in engagement with contact I3 when the signal displays a red or green indication.

Slow release relays GP and YP are provided to repeat the yellow and green positions respectively of the upper arm signal UA and are energized through obvious circuits in accordance with the position of the signal contacts 8 and 9 These relays are made slow release to take care of the time interval required for the signalmechanism to move from the yellow through the red to the green position or vice versa, to prevent a momentary change of indication at the signals to the rear of signal S At each signal location there is a direct current neutral line relay which at signal S is designated by the reference character LR This relay when energized receives direct current from the output side of a double wave rectifier RECT which has its input terminals connected to the secondary of a transformer TR The lower arm of signal S is a search light type signal LA which is similar to the upper arm signal UA except that its operating coil I4 is controlled by a circuit polarized so as to operate the signal only to the green and red positions. To guard against the possibility of a movement of the signal to the yellow position the yellow lens in the spectacle has been replaced by a red lens.

The lamp L of upper arm signal UA is normally energized by alternating current through front contacts I5 and I6 of a power off relay P0 which relay will become deenergized and open its front contacts when the local alternating current power supply fails and direct current will then be supplied to the lamp L through the back points of contacts I5 and I6 Lamp L of signal LA is energized in a similar manner through contacts I1 and N5 of the same power off relay. Alternating current is also supplied through front contacts I9 and 20 of relay P0 to the primary of transformer TRA the secondary of which is connected in series with the line circuit extending between signal S and signal S A vibrator inverter VI of a type commonly used in automobile radio circuits is provided for applying interrupted direct current to the secondary of transformer 'I'RA in the event of an alternating current power failure.

Operation Having thus described in general the location and arrangement of the various parts comprising the present invention, the operation of the apparatus ateach location will now be described in detail, the signals, relays and circuits in the accompanying drawings being shown in the positions they would assume with a vehicle V occupying section I of the trackway.

Referring to Fig. 1, due to the presence of vehicle V in section I, track relay T will be deenergized and its front contacts 38 and 2 I will be open thereby disconnecting at this location the line wires 22 and 23 that extend to the next location in advance. These line wires are employed to carry direct current energy for energizing the operation winding 1 of upper arm signal UA and also to carry alternating current for energizing the primary of transformer 'I'R With track relay T deenergized, rotor 6 of signal UA will assume its neutral biased position and the red indication will be displayed on the upper arm of signal S With energy removed from the primary of transformer TR), line relay LR will be deenergized and the energizing circuit for operating winding I4 of signal LA is broken at contact 26 which results in signal LA assuming its neutral position causing the red indication to be displayed on the lower arm of signal S Thus with a vehicle occupying section I, signal S will display a red over red'indication which means that the block in advance is occupied.

At section 2 track relay T will be energized and its front contacts 38 and 2| will close a circuit for energizing the operating winding '1 of signal UA with current of a polarity that will hereinafter be referred to as current of normal polarity. Signal UA Will be positioned to display the yellow indication as shown in the drawings and contact 9 will make up with stationary contact I2 thereby energizing the repeater relay YP through an obvious circuit. The circuit for operating UA may be traced from battery, back contact 21 of relay LR secondary winding of transformer TRA line wire .23 front contact ill of relay T winding 7 of signal UA front contact 38 of relay T line wire 22 back contact 28 of relay LE to battery.

Relay LE is normally energized by rectified alternating current from signal location S through a circuit that includes transformer TRA at signal location S and transformer TR at signal location S As previously described the secondary of transformer TR, supplies energy to the input side of rectifier REC'I for energizing relay LR. and the primary of transformer TR. is normally energized through a circuit that may be traced from the left side of the secondary coil of transformer TRA line wire 23 front contact 21 of relay T wire 29 either front contact 3B of relay YP or front contact 32 of relay GP primary of transformer TR wire 30 front contact 38 of relay T line wire 22 back contact 23 of relay LE through the local battery at signal location S back contact 21 of relay LE to the other side of the secondary coil of transformer TRA Transformer IRA) is energized through a circuit that may be traced from (i), front contact I9 of relay P0 the right 1 portion of the primary coil of transformer TRA intermediate tap of the same transformer, either front contact 2& of relay GP or front contact 25 of relay YP front contact 20 of relay P0 to F) of the source of alternating current.

As previously noted with the vehicle V in section I, the repeater relays GP and YP are deenergized and under these conditions the circuit that includes the primary of transformer TRA is open and it is therefore obvious that no energy will be supplied to the primary of transformer TR for energizing the line relay LE The operating winding I4 of lower arm signal LA is normally energized by direct current through a circuit that includes the front contact 26 of relay LR back contact 33 of relay GP and front contact 34 of relay YP but with line relay LR. deenergized energy is removed from the operating winding 14 and the lower arm signal LA is positioned as shown in the drawings to display a red indication. Signal S at the entrance to section 2 of the trackway will therefore display a yellow over red indication which denotes occupancy of the second block in advance.

Referring now to the operation of the apparatus at signal location S by reason of the fact that relay LE at signal location S is deenergized, the operating winding 1 of signal UA is energized by direct current of normal polarity, through a circuit similar to the circuit previously traced for signal UA at signal location S which actuates the signal to its yellow position and energizes repeater relay YP However, at signal location S relay LR will be energized as relay GY at location S is energized and its front contact 25 completes a circuit for energizing transformer TRA which in turn energized relay LE through a circuit similar to the circuit traced for controlling relay LE With relay LE energized contact 26 is picked Cir up thereby closing a circuit for energizing the operating winding I4 of signal LA which will now display a green indication. This circuit may be traced from battery, front contact 26 of relay LE back contact 33 of relay (5P front contact 35 of relay YP operating winding I4 of signal LA to battery. Under the above conditions signal S at the entrance to section 3 will display a yellow over green indication which denotes occupancy of the third block in advance.

Referring to the operation of signal S at the entrance of section 4 of the trackway, with line relay LR at signal location S energized, current of reverse polarity will now be applied to a circuit which includes front contacts 21 and 28 of relay LE to the operating winding 7 of signal UA which will actuate the signal to its green position as shown in Fig. 2 of the drawings. This will operate contact 3 to its right hand position and an obvious circuit for energizing the repeater relay GP will be closed at contact I0 Relay LE at this location will be picked up through an energizing circuit similar to the circuit described for energizing relay LE at signal location S with the exception that the circuit for energizing transformer TR is closed through front contact 32 of relay GP instead of front contact SE of relay YP as was the case at signal location S With relay (3P picked up and relay YP deenergized the circuit for the operating winding M of signal LA is opened at contacts 33 and 3 2- respectively and the signal LA will be energized to display the red indication. Thus it will be noted that signal S at the entrance endof section l will display a green over red indication which means that the three blocks in advance are unoccupied.

The signals to the rear of signal S will display the green ove'r red indication, the top arm signal UA at each signal location being operated to its green position due to the LR relay in advance being picked up and with the top arm signal energized to the green position the GP and Y? relays are energized and deenergized respectively thereby breaking the energizing circuit of the lower arm signal and causing it to display the red indication all in a manner previously described.

Having described the normal operation of a four-wire automatic block signal system controlled over two line wires and-employing alternating current and direct current for control purposes, the arrangement provided for operating the system in the event of a failure of the alternating current power supply will now be taken up in detail.

Let us assume that a failure of the alternating current supply occurs at signal location S it being understood that the apparatus at all the other signal locations will function in a similar manner if there is a failure of the transmission line.

An alternating current power failure at signal location S will deenergize relay P0 and direct current will be supplied to lamps L of signals UA and LA as previously described, and the closure of the back contacts I9 and of relay PO will introduce the vibrating inverter VI into the primary circuit of transformer TRA With contacts I9 and 2E closed, a'coil C of vibrating inverter V1 is energized through a circuit that may be traced from battery, back contact 23 of relay P0 front contact 25 of relay YP intermediate tap of transformer'TRA the right portion of the primary coil of transformer TRA back contact I9 of relay P0 coil C of vibrating inverter VI to battery. The energization of coil C will operate vibrating armature which is preferably of the vibrating reed type, to its upper position and close contact 3G which when closed shunts coil C thereby releasing armature 35 Armature 35 being biased slightly downward as shown in the drawings will, when released, move downward a sufficient distance to engage its associated lower contact 31 When armature 35 is in its upper position and engaged with contact 36 the circuit just described energizes the right portion of transformer IRA and when armature 35 is in its extreme downward position a circuit for energizing the other half of transformer TRA with current flowing in the opposite direction, is completed which may be traced from battery, back contact 29 of relay P0 front contact 25 of relay YP the left portion of the primary coil of transformer TRA lower contact 31 and armature 35 of vibrating inverter V1 to battery.

It will be noted that when the shunt is removed from coil C and armature 35 releases, the coil C will again become energized and attract armature 35 which will again release and make up with lower contact 3'5 when coil C is shunted. This repeated energization and shunting of coil C causes armature 35 to vibrate rapidly between its upper and lower contacts thereby applying direct current of first one polarity and then the other to the primary of transformer TRA and inducing in the secondary of transformer TRA an alternating current of a frequency corresponding to the vibrating rate of armature 35 It may be pointed out here that upper arm signals UA are inherently direct current devices, and the alternating current superimposed on their respective control circuits will not effect their operation. However, it is intended to be within the scope of the invention to employ choke means in the direct current circuit to block out the alternating current if a less inherently direct current device is employed. It will also be noted that direct current will not effect the operation of lower arm signals LA as transformers TB in the alternating current circuits: block out the direct current at that point.

The particular construction and arrangement of circuits shown and described represents only one particular embodiment of the present invention'and is merely typical or illustrative of the principles, functions, and mode of operation of the invention, and it should be understood that various adaptations, modifications, and additions may be made in this particular arrangement, without departing from the scope of the invention.

What I claim is:

1. In a signal system for railroads, in combination; a stretch of track divided into track sections; a signal located at the entrance of each track section having a first and a second indicator; an operating mechanism for each first and second indicator; one line circuit only for interconnecting adjacent signals; means for controlling said signals oy applying di t and alternating current to said one line i. iit in cordance with traffic conditions ahead, the first indicator of each signal being dis 'nctively controlled by relay means at the location next in advance, which relay means controlled by the condition of the first indicator of the associated signal and the first indicator of the signal next in advance thereof, and the second indicator of each signal of which is disinctively controlled by the condition of the first indicator of the associated signal and of the first indicator of the signal next in advance.

2. In a signal system for railroads; the combination with a stretch of track divided into track sections each having a track relay; a signal comprising two signal mechanisms located at the entrance end of each section, each signal mechanism including an electro-magnetically operated spectacle and contacts; a control circuit for one of said mechanisms including line wires extending to the signal in advance and including contacts controlled by the track relay of the section in advance and contacts controlled by the signal in advance and energized by direct current, and a control circuit for the other of said mechanism energized by alternating current flowing over the same line wires and including contacts controlled by the signal in advance and contacts controlled by said one mechanism, whereby said other mechanism depends for its operation on the position assumed by said one mechanism and also on the position assumed by the mechanism in advance.

3. In a signal system for railroads, the combination with a stretch of track divided into track sections each having a track circuit including a normally energized track relay, a signal at the entrance end of each section including electrically operated mechanism for operating a spectacle and contacts, said electrically operated mechanism being operated to a clear position if current of one polarity is applied thereto through a line circuit including front contacts of the track relay of the section in advance and controlled by the signal in advance and being operated to the caution position if current of the opposite polarity is applied thereto, two slow dropping relays associated with each signal neither of which is energized if the mechanism of said signal assumes the stop position, one relay of which has an energizing circuit including a contact of said mechanism closed only when said mechanism assumes a clear position and the other relay of which is provided with an energizing circuit including a contact of said mechanism closed only when said mechanism assumes a caution position, andmeans for applying current of one polarity to said line circuit when either of the slow dropping relays of the signal in advance is in its energized condition and for applying current of reverse polarity to said line circuit when both of the slow dropping relays associated with the signal in advance are in their retracted condition, whereby said circuit is not momentarily pole changed if the signal in advance changes from clear to caution or from caution to clear but is pole changed if such signal in advance is moved to the stop position.

4. In a signal system for railroads, the combination with a stretch of track divided into track sections each having a track circuit including a track relay, a signal at the entrance end of each section including electrically operated mechanism for operating a spectacle and contacts, said electrically operated mechanism being operated to a clear position if current of one polarity is applied thereto and being operated to the caution position if current of the opposite polarity is applied thereto, a line circuit including front contacts of the track relay of the section in advance for controlling said mechanism, two slow dropping relays associated with each signal neither of which is energized if the mechanism of said signal assumes the stop position, one relay of which has an energizing circuit including a contact of said mechanism closed when said mechanism assumes a clear position and the other relay of which is provided with an energizing circuit including a contact of said mechanism closed when said mechanism assumes a caution position, means for applying current of one polarity to said line circuit when either of the slow dropping relays of the signal in advance is in its energized condition and for applying current of reverse polarity to said line circuit when both of the slow dropping relays associated with the signal in advance are in their retracted condition, whereby said circuit is not momentarily pole changed if the signal in advance changes from clear to caution or from caution to clear but is pole changed if such signal in advance is moved to the stop position, and an auxiliary signal controlled by said slow dropping relays.

5. In a signal system for railroads, the combination with a stretch of track divided by insulating joints into track sections each including a track circuit having a track relay, two signals at the entrance end of each block one of which includes an operating mechanism capable of assuming a clear, caution and a stop position and operating a color screen spectacle and operating contacts, two slow dropping relays associated with said operating mechanism, one of said slow dropping relays having an energizing circuit including one of said contacts closed only when said mechanism assumes the clear position and the other of said slow dropping relays having an energizing circuit including another of said contacts closed only when said mechanism assumes the caution position, a line circuit extending to the next signal location in advance and including a front contact of the track relay of the track section in advance and connected to said signal mechanism and operating said signal mechanism to the clear position when energized by direct current of one polarity and operating it to the caution position when energized by direct current of reverse polarity, a transformer connected in multiple with the energizing winding. of said mechanism through a circuit including in multiple front contacts of the slow dropping relays associated with said mechanism, a signal relay for controlling a sec- 0nd signal at the same location energized from the secondary winding of the transformer at that location, and means at the signal location in advance for applying direct current of one polarity and alternating current to said line circuit when the signal relay and one of the slow dropping relays at such signal location in advance are in their energized condition and for applying only direct current of the opposite polarity to said line circuit when both slow dropping relays and the signal relay at said location in advance are in their deenergized condition, whereby said second signal at any location cannot have its control circuit energized unless its associated signal assumes either the clear or the caution position and whereby a change from clear to caution or from caution to clear of a signal mechanism will not afi'ect the signal mechanism in the rear.

DANIEL J. MURPHY. 

